The present invention relates to an exposure measuring system for a microscope attached camera wherein a photodetector may be inserted into the path of the beam of a focusing telescope.
It is known to the prior art with respect to the use of such attachment cameras to provide a focusing telescope provided with an aperture for introducing a slider into the path of the beam. Using such sliders, a reticle for observation or also a photodetector for exposure measurement is selectively introduced. The reticle and photodetector may be mounted a given distance apart on the same support. Besides the format markings, the reticle is also provided at the center with another marking, for instance a circle serving on one hand as a focusing means and on the other corresponding approximately to the size of the photodetector and therefore indicating the location at which the exposure measurement takes place. Such a microscope is disclosed in U.S. Pat. No. 2,910,913.
However, measuring the exposure rigidly at the center of the image entails the drawback that the site of the preparation typical of a general object transmissivity must be nearly at the center for an accurate exposure measurement. This is rarely the case from the start and the preparation must be displaced until such a representative site is at the center.